1. Field of the Invention
The present invention relates to a code reading apparatus and code reading method which read a one-dimensional or two-dimensional code in non-touching fashion. More particularly, it relates to a code reading apparatus and code reading method for color images, in which information expressed by the above code is recognized from a color image, and in which the recognized data of the pertinent code and the original color image data of a subject for management as specified by this code can be recorded in mapping with each other.
2. Description of the Related Art
In cases of copying and managing various kinds of printed matter, such as deeds, newspapers, books and documents (hereinbelow termed “information sources” or “subjects for management”), there has been adopted a method wherein the subjects for management are managed using microfilm, or a method wherein image data accepted by a scanner or the like are recorded on a recording medium and are managed by employing a computer. When the subjects for management as mentioned above are put into the shape of a database so as to be retrievable by way of example and are managed by utilizing a computer, codes for specifying the individual subjects for management are required. Although the codes depend also upon the sorts of the subjects for management and the purposes of the management, a code formed of the character strings of classification number, bond number, document number, a date, etc. is usually afforded in order to specify each of the subjects for management, and the pertinent subject for management is recorded on a recording medium and is managed in association with the identifying code. In this manner, the various information sources are managed by utilizing the computer, whereby the retrievals of the information sources are facilitated. Moreover, it is dispensed with to take copies of the information sources on paper or the like and to keep the copies in custody, and a space for custody can be made smaller.
Meanwhile, in recent years, one-dimensional or two-dimensional codes in each of which the No., trade name, price and other information items of a product or a component are symbolized by a bar pattern in, for example, monochrome have been extensively employed in order to recognize the numbers, trade names, prices and other information items of products or components. Such one-dimensional codes or two-dimensional codes expressed by the code patterns having different reflection factors represent a series of numerals and characters in terms of the combinations of the ratios between the widths of lines in, for example, white and black, and the numbers, trade names, prices and other information items of the products or components are replaced with the numerals and characters.
Therefore, in a case where the one-dimensional codes or two-dimensional codes are utilized as the above identifying codes for specifying the subjects for management and where management information items are further included in the codes, the labor of inputting codes anew can be saved, and it is permitted to easily manage the images of the various subjects for management. A code reading apparatus for such one-dimensional codes or two-dimensional codes recognizes each code from a white-and-black image (achromatic image), and it includes an imaging device for the white-and-black images as has a high resolution. In general, it is incarnated as an apparatus dedicated to the code reading.
Meanwhile, an example of an optical information reading apparatus furnished with the function of reading images other than codes is disclosed in the official gazette of Japanese Patent Laid-Open No. 307886/1998. The apparatus disclosed in this official gazette (hereinbelow termed the “prior art example”) is such that an image to be read and a two-dimensional code can be simultaneously accepted by a single portable terminal. More specifically, the read port of a handy scanner is directed toward the sealing area 72 of a delivery slip 70 as shown in FIG. 1 by way of example, so as to read the two-dimensional image thereof, and two-dimensional image data (multi-valued image data obtained by quantizing continuous density values) are stored in a multi-valued image memory as they are, while binary image data obtained by binary coding the multi-valued image data are stored in a two-valued image memory, whereupon the contents of both the memories are transmitted to a host computer or the like. Besides, a two-dimensional code 74 existing in the sealing area 72 is decrypted on the basis of the above binary image data, and the decrypted code data and the two-dimensional image data of the sealing area 72 can be recorded in association.
The apparatus disclosed in the prior art example stated above decrypts the code on the basis of the binary image data composed of the two levels of “1” (high) and “0” (low), and it is effective in the case of managing the achromatic information sources of the sealing information, etc. However, it is not applicable in a case where the information sources are colored, and it has such a disadvantage that the range of utilization is limited. In order to cope with color images, it is considered by way of example that a system in which the signal of any of color components R, G and B is binary coded into data for decrypting the code is applied to the apparatus disclosed in the prior art example. However, even when an imaging device of high resolution is employed, the sensitivity thereof lowers to ⅓, to pose the problem that code recognition of high precision cannot be realized. Also considered is a method in which a code reading apparatus such as a bar code reader, and an image processing apparatus are unitarily constructed, but the method poses the problems that the whole apparatus becomes large in size and that it becomes expensive.